Typical drop down armrests used in business jet aircraft seats have a mechanism that allows for generally vertical movement and positioning of the armrest. Most mechanisms consist of a touch latch type of locking device. Very commonly, the touch latch used is an M-lock style. U.S. Pat. No. 5,795,025 to Murphy illustrates the M-lock style touch latch.
A less common type of armrest uses a four bar linkage mechanism. This four bar linkage mechanism allows the arm to be adjusted vertically by swinging the armrest in a generally circular and downward motion.
When an M-lock style touch latch device is used for locking the armrest in the up position, the armrest usually only has two positions, fully up or fully down. The armrest typically requires a slight further upward movement to unlock and then the armrest is free to drop down. This design is functionally effective but has drawbacks.
The drawbacks include the noise of the lock mechanism as it engages and disengages, and noise as the armrest drops completely down. The armrest has no adjustability beyond the fully up and fully down position. Further, the slight upward movement of the armrest to disengage lock requires a gap in the finish upholstery or the use of very soft foam if a zero gap is desired. Neither option is fully acceptable, when a gap is chosen, it is unsightly, and when soft foam is chosen for zero gap, the leather and foam become prematurely worn at the compression point.
Thus, a need exists for a drop down armrest that reduces or eliminates the noises associated with adjusting the armrest, can be adjustable to any vertical position and requires zero gap in the upholstery.
A further consideration relates to the sturdiness of any such retractable armrest assembly, both in terms of general crashworthiness and in terms of being able to support the weight of a user's arms and/or upper body in the extended position. Thus, any such improved, retractable, aircraft seat armrest needs to comply with the rules and regulations of the Federal Aviation Administration relative to crashworthiness, and can be typically formed of a high-strength material. At the same time, any such improved retractable armrest assembly should be relatively lightweight and not bulky so as to maximize the fuel efficiency of the aircraft and the limited amount of seat space available within an aircraft. Such concerns may however, conflict with the general desirability of making the armrest substantially easy and uncomplicated to retract, which must also be addressed